The same applicant as the present invention filed a slit valve with the Korean patent application number 10-2003-0071906 (title of the invention: slit valve) which makes it possible to prevent the damages of a sealing member sealing the motion path and to check out the operation state with the aid of an indicator device installed at a valve driving part by improving the arrangement structures of a sealing member arranged around the motion paths of the wafer.
FIG. 1 is a cross sectional view illustrating the slit valve of the conventional art. The conventional slit valve comprises a sealing member 100 opening and closing a wafer movement path, a housing bracket 200 formed separately from the sealing member 100, a main haft 400 extended between the sealing member 100 and the housing bracket 200, an air cylinder 310 formed in the interior of the housing bracket 200 and driven by means of the pressure of air, a piston 320 disposed in the interior of the air cylinder 310, a piston shaft 330 engaged to the piston 320, a moving unit 340 engaged to the piston shaft 330 and a valve driving part 300 having a link connected to the moving unit 340 and the main shaft 340.
The slit valve is characterized in that the piston 320 of the air cylinder 310 formed in the interior of the housing bracket 200 moves up and down depending on the change of pressure of the compressed air which is externally inputted, and the moving unit 340 moves up and down along the piston, and the main shaft 400 connected to the moving unit 340 via the link 350 is driven, thus opening and closing the wafer movement paths by the sealing member 100.
As shown in FIG. 2, the valve driving part 300 of the slit valve is driven by means of a first step operation in which the main shaft 400 is driven upward and downward in a vertical direction, and a second step operation in which a semiconductor wafer movement path is opened and closed by means of the sealing member 100 as the main shaft 400 is driven forward and backward in the vertical direction, in other words, it is driven in a L shape. The L-shaped guide groove is formed for a L-shape operation.
Since the link 350 structurally rotates, the L-shape of the conventional slit valve, namely, the guide groove of the straight trajectory is not enough for the precise L-shaped motion guide of the valve driving part 300.
As shown in FIG. 2, when the link 350 is guided by means of the L-shaped guide groove 351, a stress concentration occurs due to the repeated friction at the corner between the link and the guide groove. When the link rotates being inserted into the guide groove, as shown in FIG. 2, a small margin occurs, so it is hard to accurately control the operation of opening and closing the semiconductor wafer path.
A rubber O-ring is installed at the groove at the contact surface of the opening and closing member opening and closing the semiconductor wafer movement path by mean of the link. A small degree of rotation occurs at the upper side (or lower side) O-ring when the O-ring comes into contact with the semiconductor wafer movement path. So, the O-ring rotates being installed at the groove by means of the rotation of the O-ring, so it might escape from the groove, thus being hardened.